Patients with stage III colon cancer who consumed at least two servings of nuts per week had significantly reduced risk for recurrence and death, according to the results of a prospective study (abstract 3517) presented at a press conference ahead of the 2017 American Society of Clinical Oncology (ASCO) Annual Meeting.
“This study adds to evidence that dietary and lifestyle modification can in fact yield protective benefits in colon cancer survivors,” Temidayo Fedelu, MD, a clinical fellow in medicine at Dana-Farber Cancer Institute in Boston, said during the press conference.
According to Fedelu, states of energy excess are associated with an increased risk of colon cancer death and recurrence. He noted that studies are emerging showing the benefits of nut consumption. Specifically, large prospective cohort studies showed that nut intake was associated with improved overall mortality, primarily driven by improvements in cardiovascular disease and cancer-related mortality. Other cohorts have shown that nut consumption is associated with a lower risk for type 2 diabetes, metabolic syndrome, and insulin resistance. However, the effect of nut intake on colon cancer recurrence and survival is unknown.
This study examined the effect of nut intake on colon cancer recurrence and survival among 826 patients with stage III disease who reported dietary intake with questionnaires while enrolled in a randomized adjuvant chemotherapy trial. The questionnaire assessed consumption of tree nuts, peanuts, and peanut butter servings.
Those patients who consumed two or more servings of nuts per week had a 42% decreased risk for recurrence (hazard ratio [HR], 0.58; 95% CI, 0.37–0.92; P = .03 for trend) and a 57% decreased risk for death (HR, 0.43; 95% CI, 0.25–0.74; P = .01 for trend) compared with patients who abstained from nuts.
A subgroup analysis showed that the association was confined only to tree nut intake (HR, 0.54; 95% CI, 0.34–0.85; P = .04 for trend) for disease-free survival and overall survival (HR, 0.47; 95% CI, 0.27–0.82; P = .04 for trend). Intake of peanuts or peanut butter was not associated with patient outcomes.
“Peanuts are technically legumes and this difference may be due to the different biochemical composition between peanut and tree nuts,” Fedelu said.
The researchers noted that the association of total nut intake with these improved outcomes was maintained across a variety of known or suspected predictors of recurrence and mortality including common genomic alterations such as KRAS and BRAF mutations.
Commenting on the results of the study, Daniel F. Hayes, MD, FACP, FASCO, ASCO president, said that while it was not a randomized trial, this study was conducted prospectively at the time of a clinical trial.
“That takes a lot of biases out of the classic retrospective, observational trials where patients are asked, ‘Do you remember what you did several years ago?’” Hayes said during the press conference. “That makes these findings even more compelling.”